Then why is this still worth a post? Simply because I think that it’s very easy to oversee this option and start digging in the wrong direction. In my case I believed that because a SharePoint hosted WCF Data Service is basically available at

2. If the service is anonymous you maybe could try and use the SP.RequestExecutor for which I included an example below for calling a public Rss service (Don’t forget to add the domain the service is installed in as an allowed remote endpoint to the App’s manifest). But I haven’t tested this … It’s just a thought